how to assign value 0 for DB Null

Question

User-1327394822 posted

sql  = "Select Sum(TotalAmount) from Cart where CheckedOut = 1 and OrderDate between @0 and @1";
    var orderRevenue = db.QueryValue(sql, fromDate, toDate);

if orderrevenue is Null... I want to assign 0...

I tried if(orderRevenue == null) ----- doesnt work

I tried if(orderRevenue == DBNull.Value) --- doesnt work if sum exists..

Noted: TotalAmount is "money" in sqlce

Answer 1

User379720387 posted

TotalAmount = 0;

db query here...

var ttlamount = db.QuerySingle( your query)

if (ttlamount != null) { TotalAmount = ttlamount; }

Answer 2

User-1327394822 posted

@wavemaster

Cannot implicitly convert type 'System.DBNull' to 'int'

Answer 3

User2015887388 posted

People have suggested more or less the correct answer. 

sql  = "Select Sum(TotalAmount) from Cart where CheckedOut = 1 and OrderDate between @0 and @1";
object result = db.QueryValue(sql, fromDate, toDate);
var total = result == DBNull.Value ? 0.0 : (decimal)result;

You will need to swap decimal for whatever value total amount is. If you are using SQL Sever I'd assume it was decimal and if it was SQLCE then I'd assume it was money but you may be using int if you are just learning. 

Answer 4

User379720387 posted

if ((object)ttlamount != System.DBNull.Value) { TotalAmount = ttlamount; }

Answer 5

User-1780421697 posted

Why not use

// Set y to the value of x if x is NOT null; otherwise,
// if x = null, set y to -1.

int y = x ?? 0;

Answer 6

User-1327394822 posted

var total = result == DBNull.Value ? 0.0 : (decimal)result;

it should be 0m

var orderRevenue = result == DBNull.Value ? 0m : (decimal)result;